/*
 * FileSaver.js
 * A saveAs() FileSaver implementation.
 *
 * By Eli Grey, http://eligrey.com
 *
 * License : https://github.com/eligrey/FileSaver.js/blob/master/LICENSE.md (MIT)
 * source  : http://purl.eligrey.com/github/FileSaver.js
 */

// The one and only way of getting global scope in all environments
// https://stackoverflow.com/q/3277182/1008999
const _global =
	typeof window === 'object' && window.window === window ?
	window :
	typeof self === 'object' && self.self === self ?
	self :
	typeof global === 'object' && global.global === global ?
	global :
	this

function bom(blob, opts) {
	if (typeof opts === 'undefined') opts = {
		autoBom: false
	}
	else if (typeof opts !== 'object') {
		console.warn('Deprecated: Expected third argument to be a object')
		opts = {
			autoBom: !opts
		}
	}

	// prepend BOM for UTF-8 XML and text/* types (including HTML)
	// note: your browser will automatically convert UTF-16 U+FEFF to EF BB BF
	if (
		opts.autoBom &&
		/^\s*(?:text\/\S*|application\/xml|\S*\/\S*\+xml)\s*;.*charset\s*=\s*utf-8/i.test(blob.type)
	) {
		return new Blob([String.fromCharCode(0xfeff), blob], {
			type: blob.type
		})
	}
	return blob
}

function download(url, name, opts) {
	const xhr = new XMLHttpRequest()
	xhr.open('GET', url)
	xhr.responseType = 'blob'
	xhr.onload = function() {
		saveAs(xhr.response, name, opts)
	}
	xhr.onerror = function() {
		console.error('could not download file')
	}
	xhr.send()
}

function corsEnabled(url) {
	const xhr = new XMLHttpRequest()
	// use sync to avoid popup blocker
	xhr.open('HEAD', url, false)
	try {
		xhr.send()
		// eslint-disable-next-line no-empty
	} catch (e) {}
	return xhr.status >= 200 && xhr.status <= 299
}

// `a.click()` doesn't work for all browsers (#465)
function click(node) {
	try {
		node.dispatchEvent(new MouseEvent('click'))
	} catch (e) {
		const evt = document.createEvent('MouseEvents')
		evt.initMouseEvent(
			'click',
			true,
			true,
			window,
			0,
			0,
			0,
			80,
			20,
			false,
			false,
			false,
			false,
			0,
			null
		)
		node.dispatchEvent(evt)
	}
}

const saveAs =
	_global.saveAs ||
	// probably in some web worker
	(typeof window !== 'object' || window !== _global ?
		function saveAs() {
			/* noop */
		} : // Use download attribute first if possible (#193 Lumia mobile)
		'download' in HTMLAnchorElement.prototype ?
		function saveAs(blob, name, opts) {
			const URL = _global.URL || _global.webkitURL
			const a = document.createElement('a')
			name = name || blob.name || 'download'

			a.download = name
			a.rel = 'noopener' // tabnabbing

			// TODO: detect chrome extensions & packaged apps
			// a.target = '_blank'

			if (typeof blob === 'string') {
				// Support regular links
				a.href = blob
				if (a.origin !== location.origin) {
					corsEnabled(a.href) ? download(blob, name, opts) : click(a, (a.target = '_blank'))
				} else {
					click(a)
				}
			} else {
				// Support blobs
				a.href = URL.createObjectURL(blob)
				setTimeout(function() {
					URL.revokeObjectURL(a.href)
				}, 4e4) // 40s
				setTimeout(function() {
					click(a)
				}, 0)
			}
		} : // Use msSaveOrOpenBlob as a second approach
		'msSaveOrOpenBlob' in navigator ?
		function saveAs(blob, name, opts) {
			name = name || blob.name || 'download'

			if (typeof blob === 'string') {
				if (corsEnabled(blob)) {
					download(blob, name, opts)
				} else {
					const a = document.createElement('a')
					a.href = blob
					a.target = '_blank'
					setTimeout(function() {
						click(a)
					})
				}
			} else {
				navigator.msSaveOrOpenBlob(bom(blob, opts), name)
			}
		} : // Fallback to using FileReader and a popup
		function saveAs(blob, name, opts, popup) {
			// Open a popup immediately do go around popup blocker
			// Mostly only available on user interaction and the fileReader is async so...
			popup = popup || open('', '_blank')
			if (popup) {
				popup.document.title = popup.document.body.innerText = 'downloading...'
			}

			if (typeof blob === 'string') return download(blob, name, opts)

			const force = blob.type === 'application/octet-stream'
			const isSafari = /constructor/i.test(_global.HTMLElement) || _global.safari
			const isChromeIOS = /CriOS\/[\d]+/.test(navigator.userAgent)

			if ((isChromeIOS || (force && isSafari)) && typeof FileReader === 'object') {
				// Safari doesn't allow downloading of blob URLs
				const reader = new FileReader()
				reader.onloadend = function() {
					let url = reader.result
					url = isChromeIOS ? url : url.replace(/^data:[^;]*;/, 'data:attachment/file;')
					if (popup) popup.location.href = url
					else location = url
					popup = null // reverse-tabnabbing #460
				}
				reader.readAsDataURL(blob)
			} else {
				const URL = _global.URL || _global.webkitURL
				const url = URL.createObjectURL(blob)
				if (popup) popup.location = url
				else location.href = url
				popup = null // reverse-tabnabbing #460
				setTimeout(function() {
					URL.revokeObjectURL(url)
				}, 4e4) // 40s
			}
		})

_global.saveAs = saveAs.saveAs = saveAs

module.exports = saveAs
